David Haye beat Enzo Maccarinelli inside two rounds in London early on Sunday to win their world cruiserweight unification fight.

The 27-year-old Londoner, the WBC and WBA champion, caught WBO belt holder Maccarinelli with a clubbing right hand two minutes into the second round and the referee stopped the fight seconds later with the Welshman out on his feet.

Weeks of hype had preceded the first fight between British world champions since Nigel Benn fought Chris Eubank in 1993 and there was a cracking atmosphere inside the O2 Arena as 20,000 fans greeted the fighters around 2:30 a.m. British time.

The opening round was a cagey affair with Maccarinelli, trained by Enzo Calzaghe, father of world super-middleweight champion Joe, landing the first telling blow as a confident looking Haye stood off.

However, Haye's ferocious punching power soon became evident in the second round as Maccarinelli walked on to a straight right hand. Maccarinelli withstood that one but failed to heed the warning.

With blood seeping from a small nick above his left eye, Haye unleashed another big right, catching Maccarinelli flush on the side of the head and sending him stumbling into the ropes.

Haye waded in with a flurry of punches and referee John Keane stepped in to spare him further punishment.

"I talked the talk and walked the walk," Haye, who had won 19 of his 20 previous fights by knockout, said at ringside. "I know how hard I punch and I've got my body into ridiculous condition over the last nine months.

"Enzo came here with a good record but I showed what the 'Hayemaker' is all about. No cruiserweight can live with my power and no heavyweight either."

Haye, who has been on a punishing schedule to make the 200 pounds cruiserweight limit at his training base in Miami, will now move up to heavyweight.

Maccarinelli said he was "disgusted" with his own performance in his second professional defeat from 30 fights.

"I did everything I was told not to do," the 27-year-old father of four said. "I walked in with my hands down and my head up and got caught with a great punch."